To maximize performance of computer systems and computer chips, it is important to monitor and detect vulnerabilities (e.g., noise) in the one or more voltage power supplies within the systems or on the chips. Currently, there are a number of techniques used to detect power supply noise.
One technique for detecting power supply noise is described in a paper entitled “On-Chip Voltage Noise Monitor For Measuring Voltage Bounce In Power Supply Lines Using A Digital Tester,” H. Aoki, M. Ikeda, K. Asada, Proceedings of the 2000 International Conference on Microelectronic Test Structures, 2000, pp. 112-117, which is hereby incorporated herein by reference in its entirety. This paper describes a technique that employs a comparator that compares the noisy supply to a reference voltage. The comparator requires four clocks, and the performance of the comparator strongly depends on the time constant of the capacitors in the design. The capacitors have to be sized such that the drain-to-gate capacitance of the transistors does not corrupt the measured data. Hence, this technique is extremely sensitive to sizing and does not have any calibration features.
A further technique is described in a paper entitled “On-Die Droop Detector For Analog Sensing Of Power Supply Noise,” A. Muhtaroglu, G. Taylor, T. Rahal-Arabi, IEEE Journal of Solid-State Circuits, Vol. 39, Issue 4, April 2004, pp. 651-660, which is hereby incorporated herein by reference in its entirety. This paper uses a very complicated calibration procedure that requires two 32-bit digital-to-analog converters (DACs) to generate current references. Also, each sensor requires a dedicated current reference, since the calibration features are a function of the current reference (two 32-bit DACs). Further, this approach requires two separate sensors to detect overshoots and undershoots. It also requires two current references to set different thresholds for overshoots and undershoots. Thus, this technique has a high area overhead.
Based on the foregoing, a need still exists for an enhanced capability to detect power supply noise and other power supply vulnerabilities. For example, a need exists for a non-invasive on-chip detection capability. As a further example, a need exists for an on-chip detection capability that does not employ external components in its detecting.